haskindm said:
If you have runs long enough that you need to install #8 for a 15 or 20 amp receptacle, you should probably consider installing a sub-panel and then shorter branch circuits.
I have to disagree here, we wire a lot of warehouse type buildings and you can not justify dropping a sub panel every couple of hundred feet. You would have panels with only about four circuits each.
I can tell you quite a bit of the wiring in your local Home Depot will be 6 and 8 AWG for 20 amp circuits.
Most of the chain stores we have worked with want all the panels in one or two locations, not distributed throughout.
Joe,
The largest I have had to run for 20 amp receptacle circuits has been 4 AWG CU. (per the engineer) for roof top outlets. At the receptacle location we would use a junction box and tap the 4 AWG with 10 AWG and run that to a device box.
At the panel end we installed a trough for splicing the 4 AWG to 10 AWG for the last 15' to the panel.
The short lengths of 10 AWG at each end of the up sized conductors make little difference in voltage drop over the total length.
Typical 15 and 20 amp devices will only accept 14 to 10 solid or stranded.
Breakers can be another issue. Some 15 and 20 amp breakers max out at 10 AWG while others may take a 6 AWG and if its a 600 volt breaker it might even take a 1 AWG.